Render DML RETURNING expressions through shared visitor handling

src/main/java/net/sf/jsqlparser/util/deparser/AbstractDeParser.java

@@ -9,6 +9,7 @@
  */
 package net.sf.jsqlparser.util.deparser;
 
+import net.sf.jsqlparser.statement.ReturningClause;
 import net.sf.jsqlparser.expression.ExpressionVisitor;
 import net.sf.jsqlparser.statement.update.UpdateSet;
 
@@ -26,6 +27,14 @@ protected AbstractDeParser(StringBuilder builder) {
         this.builder = builder;
     }
 
+    protected void deparseReturningClause(ReturningClause clause,
+            ExpressionVisitor<StringBuilder> visitor) {
+        if (clause != null) {
+            SelectDeParser selectItems = new SelectDeParser(visitor, builder);
+            clause.appendTo(builder, item -> item.accept(selectItems, null));
+        }
+    }
+
     public static void deparseUpdateSets(List<UpdateSet> updateSets, StringBuilder buffer,
             ExpressionVisitor<StringBuilder> visitor) {
         ExpressionListDeParser<?> expressionListDeParser =

src/main/java/net/sf/jsqlparser/util/deparser/DeleteDeParser.java

@@ -109,9 +109,7 @@ public void deParse(Delete delete) {
             builder.append(delete.getOption());
         }
 
-        if (delete.getReturningClause() != null) {
-            delete.getReturningClause().appendTo(builder);
-        }
+        deparseReturningClause(delete.getReturningClause(), expressionVisitor);
 
     }
 

src/main/java/net/sf/jsqlparser/util/deparser/InsertDeParser.java

@@ -153,9 +153,7 @@ public void deParse(Insert insert) {
             insert.getConflictAction().appendTo(builder);
         }
 
-        if (insert.getReturningClause() != null) {
-            insert.getReturningClause().appendTo(builder);
-        }
+        deparseReturningClause(insert.getReturningClause(), expressionVisitor);
     }
 
     public ExpressionVisitor<StringBuilder> getExpressionVisitor() {

src/main/java/net/sf/jsqlparser/util/deparser/UpdateDeParser.java

@@ -101,9 +101,7 @@ public void deParse(Update update) {
             builder.append(update.getOption());
         }
 
-        if (update.getReturningClause() != null) {
-            update.getReturningClause().appendTo(builder);
-        }
+        deparseReturningClause(update.getReturningClause(), expressionVisitor);
     }
 
     protected void deparseWhereClause(Update update) {

src/test/java/net/sf/jsqlparser/util/deparser/DmlReturningExpressionTest.java

@@ -0,0 +1,57 @@
+/*-
+ * #%L
+ * JSQLParser library
+ * %%
+ * Copyright (C) 2004 - 2019 JSQLParser
+ * %%
+ * Dual licensed under GNU LGPL 2.1 or Apache License 2.0
+ * #L%
+ */
+package net.sf.jsqlparser.util.deparser;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import java.util.ArrayList;
+import java.util.List;
+import net.sf.jsqlparser.expression.LongValue;
+import net.sf.jsqlparser.parser.CCJSqlParserUtil;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+class DmlReturningExpressionTest {
+    @ParameterizedTest
+    @ValueSource(strings = {"UPDATE t SET a = 7 RETURNING a + 8 AS result",
+            "DELETE FROM t WHERE a = 7 RETURNING a + 8 AS result",
+            "INSERT INTO t(a) VALUES (7) RETURNING a + 8 AS result",
+            "UPDATE t SET a = 7 RETURNING (SELECT b + 8 FROM source) AS result"})
+    void visitsReturnedExpressionsExactlyOnce(String sql) throws Exception {
+        var statement = CCJSqlParserUtil.parse(sql);
+        String original = statement.toString();
+        List<Long> seen = new ArrayList<>();
+        ExpressionDeParser expressions = new ExpressionDeParser() {
+            @Override
+            public <S> StringBuilder visit(LongValue value, S context) {
+                seen.add(value.getValue());
+                return getBuilder().append(value.getValue() + 100);
+            }
+        };
+        StringBuilder output = new StringBuilder();
+        statement.accept(new StatementDeParser(expressions, new SelectDeParser(), output), null);
+        assertEquals(List.of(7L, 8L), seen);
+        assertEquals(original.replace("7", "107").replace("8", "108"), output.toString());
+        assertEquals(original, statement.toString());
+        assertEquals(output.toString(), CCJSqlParserUtil.parse(output.toString()).toString());
+    }
+
+    @ParameterizedTest
+    @ValueSource(strings = {"INSERT INTO t(a) VALUES (1) RETURNING *",
+            "DELETE FROM t RETURNING t.*, a AS result",
+            "UPDATE t SET a = 1 RETURNING a, b INTO x, y",
+            "DELETE FROM t RETURNING WITH (OLD AS o, NEW AS n) o.*, n.id"})
+    void preservesWildcardsAliasesAndOutputTargets(String sql) throws Exception {
+        var statement = CCJSqlParserUtil.parse(sql);
+        StringBuilder output = new StringBuilder();
+        statement.accept(new StatementDeParser(output), null);
+        assertEquals(statement.toString(), output.toString());
+        assertEquals(statement.toString(), CCJSqlParserUtil.parse(output.toString()).toString());
+    }
+}